The company faced the District Court in Sydney on Friday following the gas leak on May 24, 2018, which killed Ben Pascall and Lyndon Quinlivan.

Tom Johnson was also seriously injured and was placed on life support but was released after about two weeks, with no ongoing issues.

Multiple safety shortcomings were identified at the site.

Judge David Russell issued a fine of $1,012,500, reduced from $1.35 million due to an early guilty plea.

"The penalty imposed in relation to this offence must provide for general deterrence," he said.

"Employers must take the obligations imposed by the act very seriously.

"The community is entitled to expect that small and large employers will comply with safety requirements.

"General deterrence is a significant factor when safety obligations are breached."

Hydrogen sulphide leaked from a tank at the mill following a shutdown.

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The tank had two splits, an open air vent and open access hole, and the area above it wasn't identified as a confined space.

Had it been recognised, steps would have been taken which could have prevented the tragedy.

Issues with hydrogen sulphide had been found in other areas of the mill, but not at the tank.

Concerns were raised about leaking filtrate on the day of the incident.

A worker - who later took his life after the incident - asked Mr Pascall to go up a ladder to investigate, and he fell unconscious from the gas venting from the top.

His colleague yelled out to him after several minutes after realising Mr Pascall hadn't returned before going to an elevated platform and noticing he was motionless.

Mr Quinlivan received a call a short time later and ran out of a control room with Mr Johnson to rescue Mr Pascall.

Both were also overcome.

Their colleagues performed CPR after they were taken down to the ground.

The pair's loved ones gave moving tributes when the matter was in court last week, including Jacci Quinlivan who spoke of switching off her husband's life support the following morning.

The judge said they had been left as "broken individuals".

"It would be understandable if they thought that whatever penalty I impose is inadequate," he said after noting their "searing pain and loss".

The court heard Mr Quinlivan's mother, Julie, wakes up each day and looks at his photograph before saying "another day without you".

Mr Pascall's mother Debrah still hears his voice at night saying "mummy, mum, where are you?"

On one night she heard him say "it's okay mum, I don't need anything where I am, I just need you to know how much I loved you all".

"A part of our soul is missing," she said.

Ms Pascall had been left shocked by how cold his body was at Albury hospital.

The family had to wait for hours until receiving the news of his death.

As part of the sentence, the company must create an educational video about the incident to share with other paper mills.

It no longer operates at Ettamogah, but still has a mill in Tasmania.

Half of the fine must be paid to SafeWork NSW.

Speaking after the sentence was handed down, both men's partners shared a similar sentiment - that no outcome would bring the pair back.

Georgia Webb said the legal action had answered some questions about what happened to Mr Pascall.

"I really don't think there will ever be closure," she said.

"It's too big to probably ever have closure.

"I don't think you can put a price on someone's life, so it's just a figure.

"How do you put a price on someone's life?"

Ms Webb said the trial had brought up a lot of emotions, but her loss was something that was with her each day.

"Every day you wake up and he's not there," she said.

"You go to bed and he's not there.

"Every day there are constant reminders of it.

"People do say it gets easier over time, but I can't feel it."

Jacci Quinlivian said the outcome hadn't provided any relief but thanked the judge for noting the impact the incident had had on the families.

"We're left with a life sentence," she said.

"Nothing will ever make me happy again, unless my husband was here with us.

"There's no relief in this whatsoever, there's no closure in this."

Ms Quinlivan said she would continue to push for industrial manslaughter charges to be introduced in NSW.

She has already met with people to discuss the laws - which exist in Victoria - to make her late husband proud.

"I will be fighting for justice, accountability and change," she said.

"I will not stop until my very last breath on this Earth.

"I will make my husband proud.

"Until you've been thrown into this situation, you think the laws in NSW and Australia are there to save our employees, but how can you justify getting a million dollar fine and just walking away after it's paid?"

She hopes the fine, which is towards the upper limit of $1.5 million, is a deterrent and said it was positive the judge saw the matter as being on the upper end of the scale.

"However it will never be enough for taking my husband's life and I will therefore continue to fight for industrial manslaughter laws in NSW and for companies to be held accountable for putting profits before people," she said.

"There needs to be change now.

"Lyndon's parents, sister and family remain devastated by the loss on their son and brother.

"As I have said many times before, I am the voice of my husband.

"I will continue to fight and advocate for change, justice and accountability for my husband and everyone else who has had their life stolen in preventable workplace incidents."

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A similar gas leak also occurred at the plant on December 5, 2018.

High levels of hydrogen sulphide were reported during a maintenance shutdown, but nobody was injured.

Milo Foster, who was general manager of the company at the time, had attended Albury hospital following the fatal incident to support family members.

He said, through an affidavit, that the company had given financial assistance to the families of the three men, paid for the two funerals, organised and funded counselling, provided death benefits, and helped gather $200,000 in donations to the late men's families and to Mr Johnson.

The court heard 24 safety measures were implemented to protect employees the month after the accident.

"Mr Foster expressed deep regret on behalf of Norske Skog and explained that all of its officers have felt profound grief and anguish about the deaths of Mr Quinlivan and Mr Pascall and Mr Johnson's serious injuries," Judge Russell noted.

The company, which had 166 workers at Ettamogah, had a good safety record before the incident.

Judge Russell said the business assisted authorities after the incident, pleaded guilty at an early stage and had co-operated with the prosecution at all times.

"It has taken positive steps to guard against the risk of an incident such as this ever happening again," he said.

"It has brought its documentation and its procedures into line with those which, on all the evidence, should have been in place before this accident occurred."